a
human blood typing system in which
there are 4 distinct types: A, B, AB, and O. An individual inherits an ABO type from
his or her parents and does not change it throughout life. The ABO system is not
unique to humans but is shared by many other primates including apes and monkeys.
Humans and other primates share other blood typing systems as well.

a research instrument primarily
used in physics to accelerate streams of charged subnuclear particles to high velocities
in order to sort and analyze them. This technique is now also used to count carbon
isotope atoms for radiocarbon dating. The advantage of this technique over the
conventional radiocarbon method is that it requires a far smaller sample size and can
potentially provide dates going back to around 100,000 B.P. At present, however, AMS
dates generally are for events less than 60,000 years old.

changes in the body in response to
environmental stresses such as high or low temperatures, intense
ultraviolet radiation from sun light, or high
altitude. The anatomical and
physiological
changes made in acclimatization are usually reversible.

the most well known stone
tool making tradition of Homo erectusand
early archaic humans. It
first appeared
about 1.5 million years ago or
somewhat earlier in East Africa and eventually spread throughout
Africa, Southern Europe, and South Asia. The most diagnostic Acheulian
artifact is the hand ax.

the relatively rapid
expansion and diversification of an evolving group of organisms as they
adapt to new ecological
niches. Adaptive radiation is the process by which one species
evolves into
two or more species. This occurs as a result of different populations becoming reproductively isolated
from each other, usually by adapting to different environments. The
branching pattern of evolution resulting from adaptive radiation
is known as cladogenesis .

the process by which individual
organisms respond to environmental stresses during their lifetime without changing
genetically.Adjustments are generally not inheritable.
Acclimatization
and developmental adjustment are examples of
adjustment. See adaptation.

the clumping together
of red cells in blood as a result of
antibodies attaching to
antigens
on the surface of the cells. This occurs when blood of
incompatible types is mixed together outside of the body, as for example
during blood typing. When different types of blood come into
contact within the body as a result of a mismatched transfusion, the alien red cells
usually burst instead of agglutinate.

a
slow acting disease caused by the
HIV retrovirus.
AIDS is usually fatal if not treated. Important
disease-fighting white blood cells are destroyed, resulting in a weakened
immune system. Death usually comes as a result of cancer or other
diseases that are normally fought off by healthy immune systems. HIV
is spread from person to person via bodily fluids such as blood and semen.
The common methods of transmission are via sexual intercourse or sharing
hypodermic needles.

the genetically inherited condition
in which there is a marked deficiency of pigmentation in skin, hair, and eyes. An
individual with these traits is an "albino." Since the gene for albinism
is recessive, it only shows up in the
phenotype of
homozygous recessive people.
Albinos have sunlight sensitive eyes and skin. They are also more
likely to develop skin and eye cancers. This is a
pleiotropic
trait.

an alternate form or variety of a
gene. The alleles for a trait occupy the same locus or position on
homologous chromosomes and thus govern
the same trait. However, because they are different, their action may
result in different expressions of that trait.

within the same species of
warm-blooded animals, individuals from populations living in colder environments usually
have shorter appendages than do those from populations in warmer areas.
This is because of the selective advantage it provides. Short
arms, legs, and other appendages have relatively less skin surface area
that can radiate heat into the surrounding environment.
Subsequently, the body retains more of it.Allen's Rule is a
corollary ofBergmann's Rule. Allen's
Rule was named after Joel Allen, a 19th century naturalist.

the common primate
practice of carefully picking through the hair of someone, looking for insects, twigs, and other debris.
Grooming others is a common way by which primates
communicate affection and reduce group tension. See
autogrooming.

a routine diagnostic procedure for
pregnant women to determine whether or not their fetuses have gross chromosomal
anomalies. This screening procedure
is also called maternal serum alpha-feto protein (MSAFP) testing. The
testing is comparatively inexpensive but not as reliable
as amniocentesis or
chorionic
villi sampling. With AFP sampling, blood is drawn from a pregnant woman in order
to determine the amount of alpha-feto protein that has leaked into her system from her
unborn child. Unusually high or low amounts of AFP relative to the stage of
pregnancy indicate that there may be specific kinds of genetic defects.
Specifically, it may indicate the likelihood of
Down
syndrome, neural tube defects,
abdominal
wall defects, and trisomy 18.
Low AFP levels are associated with Down syndrome, while high levels are
indicative of neural tube defects. The amounts of
other diagnostic fetal chemicals (hCG and estriol) also are measured in expanded AFP
screening or triple-screening.

the adult male and
female members of a community who are at the top of their gender based
dominance
hierarchies. Non-human primate alpha males and females usually
mate more frequently and have greater access to food.

a progressive, irreversible disease
characterized by degeneration of brain cells that commonly result in severe loss of
memory, the ability to think, and pay attention. There are also usually major
changes in personality. Alzheimer syndrome most often occurs in late middle and old
age. Genetic factors probably play a role since this syndrome is more common in some
families.

an
organic molecule that is a building blocks of
proteins. There are at least 20 different kinds of
amino acids in living things. Proteins are composed of
different combinations of amino acids assembled in chain-like
molecules. Amino acids are primarily composed of
carbon, oxygen, hydrogen, and nitrogen.

amethod for dating organic matter that is based on the fact that amino acids progressively change to mirror image
forms following the death of an organism--i.e., from L-amino acid to D-amino acid
forms. Aspartic acid in organic samples is commonly used for this dating technique.
Amino acid racemization could be considered to be a chronometricor a
calibrated relative dating
method.

members of a
conservative Protestant sect related to the Mennonites. The Amish
migrated to Pennsylvania from Switzerland in the late 18th century.
The Old Order Amish are a relatively closed group that shuns most modern
conveniences in their farming lifestyle. They use horse drawn
carriages, dress very simply, and reject those who marry non-Amish.

a diagnostic procedure for pregnant
women to determine whether or not their fetuses have gross chromosomal anomalies. It
involves sampling the liquid immediately surrounding a
fetus within
the amnion. This amniotic fluid is extracted through the
mother's abdominal and uterine walls with a
hypodermic needle. The amniotic fluid mostly contains
fetal urine but also has millions of fetal skin cells that can be cultured to produce a
karyotype. There is 99+% accuracy in diagnosing
Down
syndrome and most other gross chromosomal aberrations including
neural tube defects such as
spina
bifida.

the class of vertebrates that includes frogs,
toads, and salamanders.Amphibiansspend part of their lives under water and part on land.
They must return to damp areas to
reproduce since their eggs would otherwisedry out. They start life with gills, like
fish, and later develop lungs to breath air.

a
medical condition characterized by fatigue, weakness, poor
appetite, weight loss, and paleness or a yellowish tinge to the
skin and eyes resulting from a deficiency of red blood cells or insufficient
amounts of hemoglobin
molecules within the red cells. The result in both cases is a
significantly reduced ability to get oxygen to the cells of the
body. There are many different genetic and
environmental causes of anemia.

a chromosomal abnormality in which
there is an addition or loss of chromosomes within a set (e.g., 23 + 22 or 23 + 24).
Down syndrome is most often the result of this kind of
error. See monosomy, trisomy,
and polyploidy.

the kingdom of living things that
includes all animals. They are multicellular organisms that ingest food rather than absorb
or photosynthesize it. They also have their own means
of locomotion in at least one phase of their life cycles.

a kind of protein produced by the body to
identify and neutralize or destroy alien
antigens. Antibodies are
involved in the rejection of mismatched blood transfusions and organ
transplants. They are also responsible for recognizing and eliminating
bacteria and viruses. Antibodies provide a major defense for our bodies
against invasion by alien organisms.

molecules that provide the
specific signature or identity to blood or other tissue cells. When
alien antigens are introduced into the body, they stimulate the
production and mobilization of
antibodies. Antigens are found on the surface of blood and other
tissue cells as well as bacteria and viruses.

what the air temperature
actually feels like to people. This varies with the relative humidity of the
air. The higher the relative humidity, the higher the apparent temperature is even
if the air temperature does not change because evaporation of sweat is progressively less
efficient in cooling the body.

tree-living;
referring to animals that are adapted to life in the trees.
Arboreal animals spend most of their time scampering around in trees
rather than on the ground, in the air, or water. See
semi-terrestrial
and terrestrial.

the study of the prehistory
or
early history of societies and their cultures. Unlike paleoanthropology, the focus of
archaeology is mainly on the material remains of culture rather than biological evolution.

the variety
or species of humans that was intermediate between Homo
erectus and modern humans. The earliest archaic
humansmay have appeared shortly
after 800,000 years ago in Southern Europe and
East Africa. Elsewhere in the Old World, the
transition to archaic humans began around 400,000
years ago or later.
The most well known
late
archaic humans were the
Neandertals.
Archaic humans are also known as archaic
Homo sapiens
and premodern humans. See Homo
heidelbergensis.

a radiometric
dating method based on the changing ratio of argon-40to argon-39 with the passage of
time in volcanic rock or ash. This technique was derived from potassium-argon dating.
The argon-40/argon-39
method is usually more accurate than potassium-argon
dating and doesn't require as large a sample.

a thing that is intentionally made
according to a cultural pattern or inadvertently modified as a result of culturally
patterned behavior. Artifacts are usually relatively portable objects such as
projectile points, ceramic pots, and baskets.

an artifact type that was made by a
particular culture during a limited time period. When discovered
clearly in association with ancient humans in
an archaeological site, they are an indication of at least the relative time of
the occupation. When the independent dating of the
artifact types is reliable, this can be considered a calibrated relative
dating method.

a hypothesis to explain the origin of
modern Homo sapiens.
It proposes that the first modern humans evolved in Africa, but when
they migrated into other regions they did not simply replace
existing human populations. Rather, they interbred to a limited
degree with late
archaic humans resulting in hybrid populations. The
assimilation model is also known as the
"partial
replacement model." See
replacement model and
regional continuity model.

a species of the genus
Australopithecus. They lived during the Pliocene and
early Pleistocene geological
Epochs in Africa (i.e., ca. 4.2-1.4 million years ago).
Australopithecines and humans
are hominins.
One or more species of australopithecines probably were our ancestors.

microscopic simple
single celled organisms lacking chlorophyll and a membrane around their
nuclei. They reproduce by mitosis. Many
species of bacteria are parasites of humans and other animals and
plants. Bacteria are classified as members of the Kingdom Monera.

the measure of the total energy
utilized by the body to maintain its necessary processes
while at rest. Those processes include keeping the
heart, brain, and other organs functioning normally and the
necessary replacement of old or damaged cells. About 75% of
the food energy that we burn every day is used for these functions.
The remaining energy is used to fuel physical work or is stored in
fat reserves for when it is needed.
Basal metabolic rate also refers to the minimum level of heat
produced by the body at rest.

within the same species of
warm-blooded animals, individuals from populations living in colder environments usually
have greater body mass than do those from populations in warmer areas.
This is because of the selective advantage it provides. A massive
body produces more internal heat and radiates relatively less of it into
the surrounding environment because the skin surface area is relatively
smaller. Subsequently, a massive body produces and retains more
heat. Bergmann's Rule was named
after Carl Bergmann, a 19th century naturalist. See
Allen's Rule.

the intercontinental land connection appeared
between Siberia and Alaska that appeared at least twice during the last
ice age as a result of sea levels dropping more than 300 feet. Beringia is also known as the Bering Plain.

the
chordate
characteristic of the left and right sides of the body being mirror images of
each other. If there are two functionally similar body parts, they are usually found
roughly equidistant from the center line, parallel to each other on bilaterally
symmetrical animals.

the yellow-red
pigment of human bile. Small amounts of it are normally found in
blood and urine. At high bilirubin levels, blood and urine change color and the
skin becomes yellow or jaundiced. This is one of the symptoms of
mismatched blood transfusions and
mother-fetus incompatibility in blood type.

the Linnaean
classification system use of two Latin name
categories, genus and species, to designate each type of organism. A
genus is a higher level category that includes one or more species under it. For
example, humans are Homo sapiens, or "man who is wise"--Homo
is our genus and sapiens is our species.Binomen literally means
"two names" in Latin.Binomial nomenclature is another term
for binomen.

the pattern of
human evolution in which the effects of natural selection are altered by
cultural inventions. Culture can alter the direction of evolution by
creating non-biological adaptations to environmental stresses (e.g.,
wearing insulating clothes on very cold days). This potentially reduces
the need to evolve genetic responses to the stresses.
This has meant that we have been able to remain
essentially tropical animals biologically and live in colder regions of
our planet. Biocultural evolution can also involve a
mutual, interactive evolution of human biology and culture.
An example of this has been the selection favoring sickle-cell traitin Africa.
Human agricultural practices altered the
environment, which resulted in factors that were advantageous to both
the malarial microorganisms and the mosquitoes that transmit them
between people. This, in turn, selected for the
sickling allele.

a
species
that has been defined on the basis of the ability to produce fertile
offspring. Members of the same species can produce offspring that can
in turn reproduce while members of different species cannot. See
morphospecies.

the relative
dating of early human sites by association with index fossils
uncovered in the same strata as human evidence. The assumption is that both the
people and the species that is now an index fossil must have lived at about the same time.

a
thin, roughly parallel-sided stone flake that is at least twice as long as it is
wide. They were made out of brittle breaking materials such as flint
,
chert ,
and obsidian .
Blade flakes were preforms for the manufacture of many different kinds of
tools during the Upper Paleolithic--e.g.,
knives, hide scrapers, spear tips, drills, awls, and
burins. See
punch
flaking.

an incorrect 19th century theory
about the inheritance of characteristics. It proposed that inherited
traits blend from generation to generation. Through his plant
cross-breeding experiments, Gregor Mendel proved that this was wrong.

a dramatic reduction in genetic
diversity of a population or species resulting from an ecological crisis that wipes out
most of its members. The limited genetic diversity of the few survivors is the pool from
which all future generations are based. This is one
of thesmall
population size effects.

an animal that travels through the
trees by swinging under branches with a hand over hand motion. The smaller apes and
some New World monkeys brachiate. Brachiation is also
referred to as suspensory climbing.

a
highly
contagious disease caused by the bacterium Yersinia
pestis. It is normally spread by fleas that have taken blood
from an infected human or other animal. Symptoms include a high
fever and extremely swollen lymph nodes in the groin, armpits, and/or
throat. An agonizing death usually occurs within a few days.

a musical instrument
or noise maker consisting of a flat, elongated oval slab of rock, bone, or
wood with a hole in one end through which a string is attached. When
it is twisted and then whirled rapidly by the string, a humming or "roaring" noise
is produced. Bull roarers may be only a few inches in length or
several feet long.

use of a
relative dating method
that measures somewhat irregular occurring natural phenomena that have
been cross-dated with at least one
chronometric
technique so that the dates are somewhat comparable from sites in one
region to another. Calibrated relative methods could be considered
to be somewhere between ordinary relative methods and
radiometric
methods in terms of their ability to produce dates that closely
approximate the actual date of a sample.
Amino acid racemization and
paleomagnetic dating
are generally considered to
be either chronometric or calibrated relative methods.

the
comparatively pointed teeth on either side of the incisors, at
the front of the mouth of mammals. There is one canine tooth in
each of the four quadrants of the mouth. Canine teeth are
mainly used to pierce and tear food. See molar and
premolar
teeth.

a space or
gap between the canine and adjacent teeth. It allows room for
the point of the protruding opposite canine tooth and thereby
permits the upper and lower teeth to bite together.
Normally, there is a diastema opposite each of the four canine teeth
if the canines are significantly longer than the other teeth.

any of several
reddish-orange organic pigments. While carotene is present in
human skin, it is also found in higher concentrations in butter, carrots, and
some other vegetables. Carotene is involved in the
synthesis of vitamin A in people and other animals.

an individual who is
heterozygous for a trait that only shows up in the
phenotype of those who are
homozygous
recessive. Carriers often do not show any signs of the trait but can pass it on to
their offspring. This is the case with
hemophilia.

the view that the
Earth's geological landscape is the result of violent cataclysmic
events. Advocates of this theory usually believe that there have been a
number of wide-spread violent and sudden natural catastrophes that have destroyed
most living things. This idea was used by George Cuvier to explain
the extinction of species. Catastrophism was opposed by
uniformitarianism
during the late 18th and 19th centuries.

a presumed human "race"
consisting of Europeans and other closely related people. The classification is based on
the discredited typological model. The term "Caucasoid" was derived from
the Caucasus Mountains on the southeast
fringe of Europe between the Black and Caspian Seas. This
region was once thought to be the homeland of Indo-Europeans.

a complex unit of protoplasm,
usually with a nucleus, cytoplasm, and an enclosing membrane. All plants and animals are
composed of one or more microscopic cells. The smallest organic unit capable of
carrying out all of the functions normally attributed to life is a cell.
See eukaryotic cell and
prokaryotic
cell.

the most recent geological era,
dating from about 65.5 million years ago to the present. It is the era in which the
mammals flourished. It began as the last dinosaurs became extinct, at the end of the
Mesozoic Era. Most of the placental mammals and all of
the primates evolved during the Cenozoic.

the two large
frontal lobes at the top of the brain that make up about 85% of its weight in
modern humans. Our high level mental functions, such as speech and
processing complex information, occur in the cerebrum. The cerebral
cortex, or outer surface, is deeply convoluted. About 2/3 of the
human brain surface lies within these folds. The amount of cerebral
cortex folding, and subsequently the surface area of the brain, increased
as humans evolved from Homo habilis to Homo erectus and
ultimately Homo sapiens.

cheeks that are so elastic that
they can expand to allow temporary storage of food. This is useful when there is
competition.Old World monkey
in the subfamily Cercopithecinae (macaques, baboons, etc.)
have cheek pouches of this sort.

the phylum of animals that is
characterized by elongated bilaterally symmetrical bodies. In some phase of their
life cycle, they have a notochord and
gill slits or pouches. Chordates also often have
a head, a tail, and a digestive system with an opening at both ends of the body. The
Chordata include fish, amphibians, reptiles, birds, mammals, and 2
invertebrate subphyla
(tunicates and lancelets).

a diagnostic procedure for pregnant
women to determine whether or not their
fetuses have gross
chromosomal anomalies. It involves collecting a small sample of
chorion
cells for karyotyping. The
biopsy
usually is done by inserting a small flexible plastic tube through the
vagina
and the cervix of the
uterus to draw out a
sample of chorion tissue. Alternately, the cells may be extracted with a hypodermic needle through the uterine wall, as in the case
of amniocentesis. With CVS, there is approximately 98%
accuracy in diagnosing Down syndrome and many other
conditions due to gross chromosomal abnormalities. However, the accuracy in
predicting neural tube defects is lower than with
amniocentesis. Some sources refer to CVS as
"chorionic villus sampling". "Villus" is the singular of "villi".

a discrete, thread-like,
gene-carrying body in the nucleus of a cell. Chromosomes are
composed primarily of DNA and
protein.
They are visible only under magnification during certain stages of cell
division. Humans have 46 chromosomes in each
somatic
cell and 23 in each sex cell.

a date that places an event in its
chronological position with reference to a universal time scale such as a calendar.
Such dates usually are given in terms of the number of years before or after a calendar
starting point. For instance, 1950 B.C. was 1950 years before the beginning date of
the Gregorian calendar, which is commonly used
today. Chronometric dating methods include the use
of written records,
dendrochronology, and
radiometric
methods. See relative date.

an
approach to discovering evolutionary
relationships between organisms based
on shared derived
traits. Cladistics has largely replaced the older
approach known as evolutionary or phylogenetic sytematics which
grouped organisms together based on
homologiesin general without distinguishing
between
primitive and derived ones.

progressively changing zones of
degree difference in
frequency of a trait with movement from one region to
another. The gradual decrease in frequency of the B blood allele going west in
Europe is an example of such a gradation or clinal distribution. See
discontinuous distribution.

the situation in which two
different alleles for a trait are expressed unblended in the
phenotype of
heterozygous
individuals. Neither allele is dominant or recessive, so that both
appear in the phenotype or influence it. Type AB blood is an example. Such traits are said to be codominant.

the
development of a similar anatomical feature in distinct species lines after divergence from a common ancestor
that did not have the initial trait that led to it. The common
ancestor is usually more distant in time than is
the case with parallelism.
Convergence is thought to be due primarily to the independent species
lines experiencing the same kinds of natural selection pressures. Convergence is also referred to as convergent evolution.
Convergence results in homoplasies.

streams of highly penetrating
charged particles (composed of free electrons, protons,
alpha
particles, and a few heavier atom nuclei) that bombard the earth at high speed from outer
space. On entering our upper atmosphere, they commonly collide with gas atoms
and alter the atomic structures of those atoms.

the belief that all species were
created as they are today and that they have not undergone any evolution since then.
This view is usually based primarily on the Book of Genesis in the
Judeo-Christian Bible. Most creationists also believe that the Earth
is very young (typically about 6,000 years old). In the U.S.
creationism is the basis for what has become known as "creation
science."

the modern
Homo
sapiens who appeared in Europe by 40,000 years ago. Their
skeletons generally were lighter than the
Neandertals who occupied Europe at
that time. The Cro-Magnon had broad, small faces with pointed chins
and high foreheads. They are the ancestors of modern Europeans.

the exchange of genetic material
(DNA) between homologous chromosomes at the beginning of
meiosis. This results in
sperm and
ova with greater genetic diversity
due to a recombination of genes. Specifically, a portion of the end
of a
chromosome is broken and reattached on another chromosome.

a genetically inherited disease
in children that results in chronic fluid development in the lungs, making
breathing difficult. This disease also prevents normal absorption of
fats and other nutrients from food. Cystic fibrosis occurs as a
result of inheriting a recessive allele for if from both parents.
This is ultimately a fatal disease, but with modern medical care, about 2/3
of the people with it survive into early adulthood. About 30,000
people have cystic fibrosis in the U.S. today.

all of the material within a
cell between the nuclear and cell membranes. The
cytoplasm consists of semifluid water-rich viscous gel
and contains numerous
specialized structures, or organelles,
involved with cell function.

the study of annual growth-rings of
trees, usually for the purpose of chronometric dating
logs found in association with relatively recent archaeological sites. Tree-ring
sequences also are used as records of cycles in local climates.

the quantity of each type of tooth
(e.g., incisor, canine, premolar, and molar) in each quadrant of the mouth, counting from the
front. The human dental formula is 2.1.2.3. The Old World monkeys and apes
also share this dental formula.

a phrase Charles Darwin used to
refer to the process by which
natural selection favors
some variations resulting in their becoming more common in the next generation.
Descent with modification is another way of describing
evolution.

a change in the normal growth
patterns and development of an individual that occurs in childhood as a result of specific
cultural practices (e.g., foot binding) or other environmental processes. The
anatomical
and physiological changes that result are mostly irreversible by
adulthood. Example: stunted growth and mild mental retardation due to severe,
prolonged undernourishment.
Developmental adjustment is also referred to as "developmental
acclimatization."

an inherited metabolic disorder in
which there are abnormally high blood sugar levels. In advanced
stages, this often results in blindness from
cataracts, nerve damage,
gangrene in the feet and legs leading to amputation, heart disease, and
kidney failure. Type 1 diabetes melitis (juvenile onset diabetes)
is due to decreased production of insulin by the pancreas. Type 2
diabetes melitis is due to increased resistance of cells in the body to
insulin. The gene or genes for diabetes are
incompletely
penetrant.

a
human blood typing system in which
there are 2 distinct types: Diego positive and Diego negative. An individual inherits a
Diego type from his or her parents and does not change it
throughout life. Apparently, the only people in
the world who are Diego positive are some Native Americans and East
Asians.

Selection for or against one extreme of a
trait.In the case of
polygenic traits
that are expressed as a continuum of
phenotypes, such as human
stature, it would be selection for people who
are either very tall or very short.
The result would be a progressive increase in the form of the trait that
is being selected for and a reduction in the form that is being selected
against. In the case of a trait controlled byonly two alleles, it would be selection
against one of the alleles. When that
allele is recessive,
it is usually selection against the recessive
homozygote and for the
dominant homozygote and the
heterozygote. An example is selection against people who have a
fatal genetically inherited disease that only
shows up in homozygous recessive people. The
result would be a progressive reduction of the recessive allele in the
gene pool of the
population and, subsequently, a reduction in the number of people who
have the disease. Continuous directional selection can result in
evolution. See
disruptive
selection and
stabilizing selection.

Selection for both extremes
of a trait and against the middle.In the case of
polygenic traits that are expressed as a continuum of
phenotypes, such as human
stature, it would be selection for
both very tall and
very short people and against those who are average
in height. The result would be a
progressive increase in both of the extreme forms of this trait and a
reduction in the middle range. In the case of a trait controlled
byonly two
alleles, it
would be selection for both
recesssive and
dominant homozygotes
and against
heterozygotes.The result would be a progressive reduction in the
number of people who are heterozygous for the trait in the population.
See directional
selection and
stabilizing selection.

a visual message, or body language,
used by primates and other animals primarily to communicate anger, fear, and other basic
emotions. Displays are a strong indication of an animal's emotional
state. See agonistic display.

a large organic molecule that
stores the genetic code for the synthesis of
proteins.
Each chromosome consists
mostly of a DNA molecule. DNA is
composed of sugars, phosphates and bases arranged in a
double
helix shaped molecular structure. Segments of DNA
correspond to specific genes.

a group of
individuals arranged in rank order. In some non-human primate species,
each community has a distinct male and female dominance hierarchy.
Every individual is ranked relative to all other community members of the
same gender. In the case of rhesus macaque females, rank is determined by the
relative rank of their mothers. Depending on the species, male ranking
may be similarly
determined by the mother's rank or it may be earned in competition with
other males. Individuals who are higher in the dominance hierarchy
usually have greater access to food, sex, and other desirable things. See
alpha male and
female.

the biological sciences use the
terms dorsal, ventral, anterior, and posterior to refer to
direction within the body of a
bilaterally symmetrical
organism. These terms are illustrated in the photo on the right. Body parts on
the sides of a body are referred to as being lateral. If something is along
the longitudinal midline of a body, it is medial.

a genetically inherited form of
mental retardation usually resulting from the inheritance of an extra
autosome
21. Down syndrome individuals also typically are short and stocky in build with
short appendages. They usually have broad round faces, saddle-shaped nose profiles,
and thick tongues that are often stuck out of their mouths. The incidence of
Down syndrome children goes up rapidly with the age of the mother, particularly after 40.

the ability
to maintain core body temperature in a normal range mainly by
avoiding exposure to environmental
temperature extremes.Reptiles,
amphibians, fish, and insects are ectothermic animals. Ectothermy is also referred to as being cold blooded.
See
endothermic.

a
radiometric
dating method based on the fact that background radiation causes electrons to separate
from their atoms and become trapped in the
crystal lattice
of minerals. When odd numbers of electrons are separated, there is a measurable
change in the magnetic field (or spin) of the atoms. Since the
magnetic field progressively changes with time in a predictable way
as a result of this process, it provides an
atomic clock, or calendar, that can be used for dating purposes. This technique is employed primarily to
chronometrically date
calcium carbonate in limestone, coral, teeth, mollusks,
and egg shells. It can also date quartz
and flint.

a genetically inherited disorder
characterized by dwarfism, extra fingers, and malformations of the arms,
wrists, and heart. The majority of the known cases in the world of this
rare syndrome have been found among the Amish and 7% of them carry the
responsible recessive autosomal allele.

the abilityto maintain a
relatively constant core body temperature
regardless of external conditions by using internal physiological means.
That is to say, they
are homeothermic, or stable in core body temperature, as a result
of endothermy.
Birds and mammals are endothermic.
Endothermy is also referred to as
being warm blooded.
See ectothermic.

a fold of skin over the inner
corner of each eyelid. This is characteristic of normal
East Asians (see photo on right). It is also
typical of people with Down syndrome from any population
in the world. The presence of epicanthic folds does not imply Down's.

a blood disease of
fetuses and newborn infants caused by the mother's anti-Rh+ antibodies
agglutinating or bursting the red cells of her infant's Rh+ blood. Symptoms include life
threatening anemia,
jaundice,
fever, swollen tissues from edema,
and an enlarged liver and spleen. Serious cases are treated by
blood replacement. Erythroblastosis fetalis
is also referred to as "hemolytic
anemia" and "hydrops fetalis."

the feeling that your own group's
cultural traditions and values are correct and superior to all others. This is
usually coupled with a generalized dislike and even contempt for people who have other
cultural traditions. Ethnocentrism is universal in that all people around the world
are ethnocentric to some degree.

a cell that has a
true nucleus and that divides by mitosis. Complex single celled
creatures such as protozoa as well as all multicelled plants and animals are
primarily eukaryotes. With the exception of red blood cells, human
cells are eukaryotic. See
prokaryotic cell.

the infraclass of
therian
mammal species in which females produce a placenta to connect the fetus to the uterus.
This enables nutrients and oxygen to get to the fetus and provides a means of
eliminating waste products. As a result, eutherian mammals can carry their young
within the uterus until late in fetal development. This has a selective advantage
because it results in decreased infant mortality. Eutherian mammals are also called
placental mammals. Included in this infraclass are dogs, cats, bears, whales,
monkeys, humans, and many other mammals.

genetic change in
a populationof organisms that occurs over time. The term is also frequently
used to refer to the appearance of a new species. More specifically, it
is change in the
frequencies of alleles in a population'sgene pool
from one generation to the next.

an unborn child during the later
stages of pregnancy. In humans, an embryo usually becomes a fetus after the 8th week
of gestation. Unlike embryos, fetuses have clearly
recognizable physical characteristics of the species and gender.

a radiometric
dating method based on the fact that when trace amounts of uranium-238
fission there is a release of highly energy-charged
alpha
particles which burn narrow fission tracks, or damage trails, through glassy materials
such as obsidian (i.e., volcanic glass),
mica, and zircon crystals. The number of fission tracks is directly
proportional to the time since the material cooled from a molten state.
The rate at
which fission tracks occur is related to the half-life of uranium-238, which is
approximately 4.5
billion years.

a
relative
dating method based on the fact that bones buried in the ground progressively lose
nitrogen and gain fluorine and other trace elements. The rate at which these changes
occur depends on the local environment. If two bones from the same site have
markedly different amounts of nitrogen and fluorine, it is a strong indication that they
did not come from the same time period. The bone with the least amount of nitrogen
and the greatest amount of fluorine is most likely the oldest.

the hole at the base of a skull
through which the spinal cord passes. Literally,
foramen magnum means a
"large hole or opening" in Latin. The position of the
foramen magnum
is a strong indicator of the angle of the spinal column to the head and subsequently
whether the body is habitually horizontal (like a horse) or vertical (like a monkey).

any remains or traces of ancient
organisms. Often fossils are mineralized bone, though they
have also been found in the form of casts, molds, animal tracks,
frozen or desiccated bodies, and creatures trapped in amber.

a small population
size effect in which
the genes of a few people (the population founders) are inherited over
time by a large number of descendents. This is also known as the "founder
effect" and the "Sewall Wright effect." See
genetic
drift.

a relatively common genetically
inherited abnormality of the X chromosome which results in mental
retardation. Since it is an X-linked trait, males more often have it expressed in their
phenotypes. Most fragile-X
males have large testes, big ears, narrow faces, and sensory integration
dysfunctions that result in learning disabilities. It is likely to occur
1 in 1000 births. Approximately 1 in 700 females are carriers of the gene
for this trait.

a reproductive cell--sperm or
unfertilized ovum cell produced in the testes and
ovaries of animals. Gametes are produced by
meiosis.
They normally have half the number of
chromosomes found in
somatic cells.

the transference of
genes
from one population to another, usually as a result of migration. The
loss or addition of individuals can easily change the
gene
pool frequencies of both the recipient and donor populations--that is,
they can evolve.

a unit of inheritance usually
occurring at a specific location, or loci, on a
chromosome.
Physically, a gene is a sequence of DNA bases that specify the order of
amino acids in a protein or, in some cases, a small
RNA molecule referred to as a
microRNA. A gene may be made up of hundreds to thousands of DNA bases.
Genes are responsible for hereditary characteristics.

evolution, or change in
gene pool
frequencies, resulting from random chance. Genetic drift
occurs most rapidly in small populations. In large
populations, random deviations in allele frequencies in one
direction are more likely to be cancelled out by random changes
in the opposite direction.

the study of gene
structure and action and the patterns of inheritance of traits from parent
to offspring. Genetic mechanisms are the underlying foundation for
evolutionary change. Genetics is the branch of science that deals with
the inheritance of biological characteristics.

the full genetic
complement of an individual (or a species). In humans, it is
estimated that each individual possesses approximately 3 billion
nucleotides
in all of the DNA that makes up his or her
genome. See Human
Genome Project.

a relative
dating method based on the association of early human sites with changing features of
the land, such as the advance and retreat of glaciers or the rise and fall of sea levels.
When these events are well dated, geochronology could be considered a
reliable calibrated relative dating technique. Associated evidence
may be changes in the frequency of plant species measured by pollen
count and other kinds of
paleoecology evidence.

A
long period of time during which earth's climate
cools, causing glaciers to expand
out from the poles and mountains covering vast areas.
The glacials of the Pleistocene Epoch mostly occurred in the northern
hemisphere. See
interglacial.

within the same species of
warm-blooded animals, there is a tendency for darker,
more heavily pigmented skin to occur in
animals near the equator and lighter pigmented skin farther from it.This
is because of the selective advantage the coloration provides. Heavy
pigmentation protects from skin cancer caused by ultraviolet radiation
from the sun. However, too much pigmentation can significantly
reduce the skin's ability to produce vitamin D, which is necessary for
the absorption of calcium and phosphorus from food. Open country
close to the equator typically experiences high amounts of intense
ultraviolet radiation while temperate and arctic regions have relatively
little. Subsequently, heavy skin pigmentation is an advantage near
the equator but a disadvantage farther away from it. Gloger's Rule
was named after Wilhelm Gloger,
a19th century naturalist.

the theory
that living things were divinely created and exist in an infinite
and continuous series of forms, each one grading into the next, from
simple to complex. This view goes back to the ancient Greeks
and was popular from the Middle Ages through the 18th century in
Europe.

long depression in Southwest Asia
and East Africa caused by the movement of tectonic
plates, largely beginning during the Oligocene
Epoch. In Africa, it extends from Ethiopia southwest 1200 miles
through the lake regions. Many of the early hominin discovery sites are in this
valley system.

a genetically
inherited X-linked error in metabolism caused by an inadequate amount of the enzyme
glucose-6-phosphate dehydrogenase in red blood cells. When exposed
to certain environmental influences, such as fava beans and some
drugs (sulphonamide antibiotics, some antimalarials including primaquine,
and several other sulphur-containing drugs) , the red cells of individuals with this deficiency burst,
resulting in severe anemia. As in the case of
sickle-cell trait
and thalassemia, this
anemia may provide some immunity to
falciparum malaria. G6PD deficiency
is also known as "favism." It is the most common type of human
enzyme deficiency--about 400 million people
have this condition around the world. It is a common problem especially
in populations around the Mediterranean Basin, the Middle East, and
Southeast Asia.

the most commonly
used calendar system in the world today. It is based on the older Julian
calendar of the late Roman Empire but more accurately corresponds to the solar
year of 365.2422 days. The Julian calendar year is 365.25 days.
This is inaccurate by approximately 11 minutes a year. The result is
that the Julian calendar is out of sync by one day every 131 years. The
Gregorian calendar fixed this problem by changing the rules for leap
years. In the Julian system, a day is added to the end of February
every 4 years. In the Gregorian system a year is a leap year if it is
divisible by 4 unless it is divisible by 100 but not by 400. This
eliminates leap years periodically in order to keep the calendar more
synchronized with the solar year. The Gregorian calendar was
named after Pope Gregory XIII who officially approved it in 1582 A.D.
England and its colonies did not adopt it until 1752.

the amount of time for half of the
atoms of a radioactive element in a sample to decay, or fission. The reduction in
the number of atoms follows a geometric scale--at the end of 2 half-lives, there
are
1/4 of the atoms left; at the end of 3 half-lives, there
are 1/8 remaining; etc.

a
rock
core or large flake
that has been systematically worked by percussion flaking to an elongated oval
bifaceshape with one pointed end and sharp edges on the sides. In profile,
hand axes usually have a teardrop or leaf shape. Hand axes are diagnostic
tools of the Acheulian
tool
tradition
of Homo erectus after about
1.5 million
years ago. They continued to be made and used by early
archaic
humans. Very likely, they were multipurpose
implements used for light chopping of wood, digging up roots and bulbs,
butchering animals, and cracking bones.

the equation (p▓+2pq+q▓ = 1) used
by population geneticists to determine probablegenotype frequencies of a
population for specific traits. By comparing these frequencies for subsequent
generations, it is possible to track the direction and rate of evolution.

The X and Y chromosomes of males are
mostly not homologous--they
only share a few genes. Those genes that are found on only the
X or the Y chromosome are said to be hemizygous because there is
only one copy of each gene. Regardless of whether that gene is
a dominant or a recessive allele, it will be expressed in the
phenotype of males.

an
X-linked
genetically inherited recessive disease in which one or
more of the normal blood clotting factors is not produced. This results in prolonged
bleeding from even minor cuts and injuries. Swollen joints caused by
internal bleeding are a common problem for hemophiliacs. Hemophilia most often afflicts males.

an
individual who has one or more testes and ovaries
and whose external genitalia are not clearly male or female. This
condition can occur in chimeras
who have inherited both a male and a female set of sex chromosomes.
True hermaphrodites have one testes and one ovary.
Male
pseudohermaphrodites, or "merms," have testes but no ovaries and
display some female genitalia tissue. Female pseudohermaphrodites,
or "ferms," have ovaries but no testes and display some male genitalia
tissue.

increased
health of individuals who are the result of
negative
assortative mating, or crossbreeding.
This is due to the fact that when mates are
from very different genetic lines they
are more likely to have lower frequencies of homozygous recessive
conditions. Subsequently, they are liable to be more viable. This
phenomenon has also been referred to as hybrid
vigor.

an arrangement in terms of rank or
importance. The Linnaean classification system of living things is hierarchical--it
is a system of classification with the highest category consisting of all living things.
Lower down are levels of less inclusive sub-categories. The lowest
sub-category is a species.

referring to the over 100
antigens on the surface of human body tissue cells that can be recognized
by some kinds of leukocytes
and potentially lead to the rejection of these tissues if they are alien.
The HLAsystem has the most
genes of any other
known human multiple-allele series.
There
are at least 30,000,000 possible HLA
genotypes.
When organ transplants fail, it is usually due to HLA incompatibility.
This can be prevented by making sure that the donor and the recipient have
the same or very similar HLA types. Immunosuppressant drugs also are
now available to restrain the HLA system and thereby allow successful
transplants when there is an HLA incompatibility between donor and
recipient. HLA stands for "human
leukocyte antigen"
.

the species of
humans that followed
Homo habilis and preceded
Homo sapiens in
our line of evolution. Homo erectus evolved in East Africa
by 1.8 million years ago. They were the
first humans to expand their range into Asia and Europe. By
at least 400,000 years ago
or even earlier in some areas, they were beginning a transitional
evolutionary phase that would eventually lead to
archaic humans. See Homo ergaster
andHomo
heidelbergensis.

An early form of the
species Homo erectusfrom
East Africa. In an alternate interpretation, some
researchers consider Homo ergaster to be the species that immediately
preceded Homo erectus in our line of evolution. Homo
ergaster fossils date about 1.8-1.5 million years ago.

a transitional
species between the australopithecines and Homo
erectus. Homo habilis appeared by 2.4
million years ago and continued until about 1.6 million years ago.
They lived in East and possibly South Africa.

A
very early form of archaic humansin Europe and North Africa
that lived from about 800,000 to 200,000 years
ago. In an alternate interpretation, some
researchers consider Homo heidelbergensis to be a separate
species or even a late advanced Homo erectus in
transition to archaic humans. Homo
heidelbergensis may have been the ancestor of the
Neandertals.

An early form of the
species Homo habilis.
In an alternate interpretation, some researchers consider Homo
rudolfensis to be the species that immediately preceded Homo habilis in
our line of evolution. Homo rudolfensis fossils date 2.4-1.6
million years ago.

the genus (Homo) and
species (sapiens) categories to which modern humans belong. Homo sapiens evolved from
Homo erectus over several hundred thousand years beginning
at least 400,000 years ago. The first
modern Homo sapiens evolved from
archaic
humans by about 130,000 years ago
in Africa. Modern humans are referred to as Homo sapiens
sapiens. The last sapiens refers to our sub-species or variety
designation.

the species designation
given to the Neandertals by researchers who
believe that these ancient people were genetically close enough to Homo
sapiens to assign them to the same species but a different
sub-species or variety. See Homo
neanderthalensis.

chromosomes
that are paired during meiosis. Such
chromosomes are alike with regard to size and also position of the
centromere. They also have the
same genes, but not necessarily the same
alleles, at the same locus
or location. All autosomes
and the sex chromosomes of females occur in homologous pairs. The
sex chromosomes of males are
mostly
hemizygous.

similar anatomical structures in
different species that were not present in their common ancestor. Homoplasies are
also referred to as homoplastic structures or features. Homoplasies can be due to
parallelism,
convergence,
or even chance.

having the same
allele
at the same locus on both members of a pair of
homologous
chromosomes. Homozygous also refers to a
genotype
consisting of two identical alleles of a gene for a particular
trait. An individual may be homozygous dominant (AA) or
homozygous recessive (aa). Individuals who are
homozygous for a trait are referred to as homozygotes. See
heterozygous.

a class
of substances (usually
proteins) that are produced by specialized cells and that travel to other
parts of the body, where they influence chemical reactions and regulate
various cellular functions. Hormones include the secretions of the
endocrine glands that affect metabolism and behavior.
Testosterone,
estrogen, and insulin are examples of such hormones.

a multinational research effort designed to
identify and map the location of all human genes. The idea of a Human
Genome Project began at a 1984 international conference in Utah.
Research to decode the human genome began in earnest in 1986, funded by
the U.S. Department of Energy. The initial stage of discovering all
human DNA codons was completed
early in 2001 at a cost of 2.7 billion dollars. The next phase of
research will be to identify the proteins for which these
genes
code. This decoding of the human
proteome will be an even
more daunting task than the original Human Genome Project. See
genome.

a severe genetically
inherited fatal degenerative nerve disorder. The symptoms usually do
not appear until early middle age. There is a progressive loss of
muscle control that inevitably leads to paralysis and death. This
disease is also called Huntington's chorea.

a
horseshoe-shaped bone in the neck above the larynx supporting the base
of the tongue. Since jaw, tongue, and larnyx muscles are anchored
to it, the hyoid bone is essential for the production of sounds used in
human speech. Humans are the only primates that have their
hyoid bones high in the neck. Subsequently, they can produce a
wider range of vocal sounds than other primates.

a small region
near the base of the brain that controls the sympathetic nervous system,
which in turn regulates the autonomic functions of the body, including
beating of the heart, breathing, and body temperature control.

oxygen deprivation. This condition
can occur at high altitude. Symptoms include a reduced ability to do work,
fatigue, dizziness, nausea, and an inability to effectively perform memory intensive
tasks. Even moderate hypoxia results in the death of some individuals
due to heart failure. In very high
mountain areas, hypoxia can cause
pulmonary edema and/or
cerebral edema, both of
which are life-threatening conditions that are aspects of what is often
referred to as acute mountain sickness.

the situation in which an
allele is expressed only if certain factors are present in the
environment. The triggering of genetically inherited
diabetes
by obesity and possibly severe emotional stress is an example.

The reduction in viability and
subsequent loss of reproductive potential of purebred varieties.
This is a consequence of a pattern of consanguineous matingthat goes on for many generations in a family line or a
small inbred population.

chisel shaped teeth at the front of
the mouth in mammals. All primates normally have 8 incisors
(2
in each quadrant of the mouth). The common mammal
pattern is 12 incisors (3 in each quadrant). See
dental formula.

remains of a plant or animal of a
species that is known to have lived only during a specific time period. The
discovery of such a fossil in an archaeological site is circumstantial evidence of the
approximate time period that it was occupied. Fossil bones of horse and elephant
related species are often used to relatively date fossils of
our ancestors. Index fossils are used for
biostratigraphy.

Lamarck's theory that evolution
occurs as a result of an organism acquiring a change in form due to using or not
using particular body parts during its lifetime and then passing the new trait on to its
offspring. This is also referred to as the "use-disuse
theory."

A
long period of warmer conditions between
glacials when the earth's glaciers have shrunk to a
smaller area. Interglacials
during the Pleistocene Epoch lasted 10's of thousands of
years. We are probably in an interglacial at
present.

sections of
DNA molecules
that do not code for proteins
but still perform important functions. Apparently, some are
enhancers or suppressors of genes.
About a fourth
of DNA consists of introns. The remaining "junk" DNA, that makes up three fourths of
a DNA molecule, very likely also has subtle functions. For
instance, It helps determine
the shape of chromosomes and also buffers against change by absorbing
the mutagenic
effect of radiation and viruses. See
exons.

a set of medical procedures to
help a couple have children if they have not been able to in the past due
to low sperm count, blocked fallopian tubes, and some other causes
of infertility. The woman is given fertility inducing drugs to cause
her to ovulate numerous ova which are surgically removed and fertilized
outside of her body with sperm from her mate or another donor. Two
or more of the fertilized ova are then placed into her uterus in the hope
that one or more will attach and develop into viable embryos. As a
result, multiple births are relatively common with IVF.

a standardized arrangement of
pictures of an individualĺs chromosomes
cut out from a microphotograph of a cell and rearranged into
homologous pairs
according to size and other physical characteristics. The standardized
arrangement of karyotypes allows medical researchers to discover if an
individual is a male or female and if he/she has any gross chromosomal
abnormalities.

relationships that are recognized between
individuals based on family ties. Among humans, those ties are created
by marriage and shared descent from ancestors. Among non-human
primates, they are due to descent.

a genetically inherited
sex chromosome abnormality only affecting males.
Genotypically, they are XXY or more rarely XXXY,
or XXXXY. They
have asexual to feminine body contours as well as breast enlargement and relatively little
body hair. They are sterile or nearly so and their penis,
testes, and
prostate gland are
small. Like metafemales, most Klinefelter
syndrome men are an
inch or so above average height. They usually have
slight learning difficulties, especially with language. However, most are sufficiently ordinary in appearance
and mental ability to live in society without notice. The frequency of
Klinefelter syndrome has been reported to be between 1 in 500 and 1 in 1,000 male births. Males
with Down syndrome sometimes also inherit Klinefelter syndrome.

the form of four legged
locomotion used by gorillas and chimps. They walk on the soles
of their feet but not on the palms of their hands.They bend their fingers and support the head
end of their
bodies with their knuckles instead of their open palms.

the disease of
babies and very young
childrenresulting from long-term
severe protein deficiency in the diet.
There is usually an associated deficiency in the consumption of vitamin A and
E as well as zinc and selenium.
Symptoms include edema (or swelling) due to water retention (especially in
the abdomen), stick-like legs and arms with little fat or muscle mass,
apathy, and loss of hair and skin pigmentation in patches. As in the
case of marasmus, children with
kwashiorkor are likely to have their growth retarded.
Kwashiorkor usually results from a child being weaned too early
and being forced to subsist mainly on a high carbohydrate and low protein
diet.

an
enzyme
produced by mammals to break down lactose in milk that they
consume. Lactase is needed for the digestion of uncooked dairy products. Lactase
deficiency results in diarrhea and other symptoms of physical intolerance of most dairy
products.

a class of cancers of the blood
cells and blood-forming organs resulting in exceptionally high leukocyte (white blood
cell) production. Other organs can become involved as well. Leukemia can be
caused by some viruses, chemicals, and radiation. However, there also may be a
genetic connection. For instance, individuals with
Down
syndrome have a much higher chance of developing leukemia.

the
so-called white cells in blood. They exist in variable numbers and
types but make up a very small part of human blood volume. Some leukocytes
(i.e., lymphocytes )
provide a physiological defense against infection. As a result, their
numbers increase when the body is under attack by
bacteria
and viruses. Some other types of leukocytes
(i.e., macrophages ) have the function of getting rid of old unneeded
blood cells. See stem cells.

flakes
of more or less standardized shapes and sizes made with a specific technique
in the Mousterian
tool tradition of
the Neandertals
and some of their contemporaries. Flint and other brittle
fracturing rock cores were percussion flaked
on one side until a convex "tortoise shell" shape was formed.
Then, a heavy percussion blow at one end of the core removed a large flake
that was convex on one side and relatively flat on the other.
This was a Levallois flake.

referring to the classification
system in use by the biological sciences today to classify all living things. It
lumps organisms together based on presumed
homologies. The
assumption is that the more homologies two organisms share, the
closer they must be in terms of evolutionary distance. The
higher, more inclusive divisions of
the Linnaean system are created by including together closely
related clusters of the immediately lower divisions.
The result is a
hierarchical
system of classification with the highest category consisting of
all living things. The lowest category consists of a single
species. Each of
the categories above species can have numerous subcategories.
The Linnaean system was
invented by Carolus Linnaeus
in the 18th century.

a group of similar life threatening diseases
found mostly in tropical and subtropical regions of the world.
Malaria is caused by any of four different microorganisms called plasmodia
(Plasmodium falciparum, vivax, ovale, and malariae).
These single-celled organisms are transmitted from person to person mostly by
anopheles mosquitoes as they extract blood. Symptoms of malaria
include chills, high fever, and sometimes fatal irregularities of the
brain, liver, kidney, and/or blood. There are at least 100,000,000
new cases of malaria reported annually around the world.
Approximately 1,500,000 people die from it each year (mostly
children--3,000 children die of malaria every day).

the medical condition
resulting from prolonged famine. Symptoms include
extreme emaciation, diarrhea, anemia, and apathy. Women with marasmus
usually stop ovulating. The loss of insulating body fat makes people
with marasmus highly vulnerable to death resulting from a drop in core body
temperature when the air falls below 60-65░ F. Children who survive
marasmus usually develop short adult stature and some degree of
permanent brain damage. See
kwashiorkor.

the cell division
process in
specialized tissues of female ovaries and male testes which results in the production of
sex cells, or gametes. Meiosis
involves two divisions and produces four
sperm cells in males and one
ovum
in females from a starting cell. Each sperm and ovum contains only
half the original number of chromosomes--23 in the case of humans.
Subsequently, meiosis is also called "reduction division."
Spermatogenesis is the term used for meiosis in males and o÷genesis refers to the same process in
females. See
mitosis.

a dark colored organic pigment
produced in the skin. There are two forms of melanin----pheomelanin,
which is red to yellow in color, and
eumelanin,
which is dark brown to black. People with light complexioned skin
mostly produce pheomelanin, while those with dark colored skin mostly
produce eumelanin. High concentrations of melanin near the surface of the skin result
in a darker complexion. Suntanned skin also has higher concentrations of melanin.

the
geological era immediately preceding the
Cenozoic Era
and dating approximately 251-65.5 million years ago. The Mesozoic
was the era in which the dinosaurs flourished and the first
mammals and birds evolved.

the form of
RNA that
carries a copy of a specific sequence of genetic information (a gene) from the
DNA
in the cell nucleus to the
ribosomes in
the cytoplasm where it is translated in order to
synthesize a protein. Messenger RNA is assembled on one
strand, or side, of a DNA molecule.

the chemical and physical
processes continuously going on in the cells of living organisms.
These are the
processes by which energy and matter are made available for use by the cells
of an organism. Heat is a byproduct of metabolism.

a genetically inherited sex
chromosome abnormality only affecting females. Metafemales inherit three X
chromosomes--their genotype is XXX. As adults, these
individuals are usually an inch or so taller than average with unusually long legs and
slender torsos. They have normal development of sexual characteristics and are
fertile. They may have slight learning difficulties and are usually in the low range
of normal intelligence. They tend to be emotionally immature for their size during
childhood. None of these traits prevent them from being socially accepted as
ordinary women. This type of chromosomal abnormality is apparently rare and little
is known about it. However, the frequency is approximately 1 in 1,000 female infants
and it may be more common when the mother is older. Metafemales are also called"triple-X females."

the infraclass of
therian
mammal species in which females bear their young in an immature condition (while still in
the early fetal stage) and then permit their further infant development in an abdominal
pouch covering their mammary glands. Compared to the delayed births of
placental mammals, this is inefficient in keeping young
infants alive. Metatherian mammals are also called marsupials. Included in
this infraclass are kangaroos, koalas, opossums, etc.

an extremely
rare genetically inherited condition in which babies are born with
extremely small brains and heads. This fatal condition has been
found only among the children of 23 Old Order Amish families in Lancaster
County Pennsylvania.

a very short form of
RNA
in the nucleus of cells. Micro RNA molecules are typically only
20-25 base units long. They are transcribed from
DNA, but are not
involved directly in protein
synthesis like other forms of RNA. They perform important functions similar to enzymes in regulating
chemical reactions in our cells, especially in the embryonic stage at
the beginning of life. It is thought that 1/3 or more of human
genes are controlled in some way by micro RNA molecules.
At least 200-255 human DNA genes code for the production of micro RNA
molecules.

an archaeological
term referring to composted soil resulting from a refuse heap left by humans
in the past. Middens often contain artifacts and food refuse remains
such as bone and mollusk shell fragments.

the part of the
Paleolithic
stage of development in which the
Mousterian
tool tradition
of the Neandertals and early modern humans was
used.The Middle Paleolithic began about
75,000 years ago and continued until at least 28,000 years ago.

inorganic, naturally occurring
materials consisting of specific elements. They are usually rocks with a
characteristic crystalline structure and other identifiable physical traits. Quartz,
talc, and ordinary table salt are examples of minerals.

small rod-like structures in the
cytoplasm that produce fuel for the cell in the form of adenosine
triphosphate (ATP). A small amount of
DNA
in a circular looping chromosome is located in
mitochondria. This DNA is normally inherited only from mothers and is distinct from DNA that
makes up the chromosomes
within the cell nucleus.

The name
given by advocates of the
replacement
model of modern Homo sapiens to the last presumed common ancestor of modern
humans based on a comparison of
mitochondrial
DNA from around the world. She is presumed to have
lived about 200,000 years ago

the simple cell division process that
occurs in somatic cells. One cell divides into two
offspring cells that are identical to each other in their chromosome complement.
Mitosis produces cells with diploid numbers of
chromosomes--46 in the case of humans. See
meiosis.

the comparatively large grinding
teeth at the back of the mouth in mammals. In hominids and
all other anthropoids, there are normally 3 molars in each
quadrant of the mouth. See premolar and canine
teeth.

identical twins. Twins that
come from the same zygote and are, subsequently, the same
genetically in terms of their nuclear DNA. Any differences between monozygotic twins later in life are
mostly the result
of environmental influences rather than genetic inheritance. Fraternal
twins may look similar but are not genetically identical. Monozygotic
twins may not share all of the same sequences of
mitochondrial DNA.
This is due to the fact that the
mitochondria in a cell
may have somewhat different versions of DNA, and the mitochondria can be
dispersed unequally when a zygote fissions. Female monozygotic
twins can also differ because of differences between them in
X-chromosome inactivation. Subsequently, one female twin can have
an X-linked condition such
as muscular dystrophy
and the other twin can be free of it.

a genetic pattern in which an
individual has two distinct cell groupings--one with normal cells and another with a
genetic problem. For instance, some people with
Down
syndrome produce both normal
somatic cells
and cells with an extra

a pattern of
evolution in which different parts of the body evolve at different
rates. In the case of humans, we essentially attained our modern form
below the neck by at least 2 million years ago. However, our
cranial
capacity did not reach its current size until after 100,000 years ago.

the situation in
which a mother's blood type is different from that of her unborn
child. In the case of some combinations of types, the mother's blood
system can produce antibodies to
antigens on the surface of the red cells of
her fetus resulting in their agglutination.
This is the case when the mother is Rh- and her fetus is Rh+. As a
result of this incompatibility, the fetus can develop
erythroblastosis
fetalis.

a genetically inherited progressive
disease of the central nervous system. MS occurs as a consequence of
one's own immune system attacking the insulating sheath that normally
protects neurons. Symptoms range from numbness and tingling to
paralysis. There is a loss of motor and cognitive functions. The gene(s) responsible for MS are
incompletely penetrant in that the onset of the disease
is apparently triggered by a virus
and possibly other environmental factors.
There is a correlation between the amount of
sunlight that children are exposed to and the likelihood that they will
develop MS later in life. People who spend much of their first 16 years
in tropical and subtropical regions of the world are much less likely to
develop this disease than those who live in far northern and far southern
regions of our planet. It is believed that the lack of abundant sun exposure early in
life is somehow responsible for the later onset of MS.

any of a group of inherited
progressive muscle disorders caused by a defect in one or more
genes
that control muscle function. MD is characterized by a gradual, irreversible
wasting of skeletal muscle. It is a
sex-linked trait
most often passed on to sons by their mothers. The most common form, Duchene MD,
begins to weaken the legs of boys by age 3 and inevitably gets worse with each passing
year. There is no cure for this disorder, and it usually results in death before the
age of 30.

an alteration of genetic material
such that a new variation is produced. For instance, a trait that has only one
allele (A) can mutate to a new form (a).
A mutation can be a change in DNA bases or changes in chromosome number
and /or structure. Mutation is the only mechanism of evolution
that can produce new alleles of a gene. See
mutagen.

an evolutionary mechanism
that
occurs when some individuals of a population are better able to adapt to their environment
and, subsequently, produce more offspring. Nature, in effect, selects which members
of a population are fit to survive long enough to reproduce.
Differential reproductive success among individuals is the key. Those who produce more
offspring have a greater influence on the gene frequencies of the next generation.
This mechanism of evolutionary change was first described by Charles
Darwin.

the most well known late archaic
humans. They lived mostly in Europe and the Near East from
150,000 years ago or even earlier until at sometime after 28,000 years
ago. There is an on-going debate as to whether they should be
considered Homo sapiens or a distinct but related species. If
they were members of our species, they were a different variety or race
(Homo sapiens neanderthalensis). On the other hand, if they were
different enough to be a distinct species, they should be considered to
be Homo neanderthalensis.

a presumed human "race"
consisting mostly of sub-Saharan Africans. This classification is based on the
discredited typological model. The term "Negroid" was derived from the
Latin word for the color black.

defective developments of the brain
or spinal cord. By the mid embryonic stage (5 weeks in humans), a neural tube
extends from the top of the head to the lower end of the
spinal column. Later, this
tube becomes the brain and spinal chord.
Spina bifida and
anencephaly are examples of neural tube defects.

a mechanical error that can occur
during meiosis and
mitosis.
Specifically, members of a pair of
homologous
chromosomes move to the same pole rather than opposite poles. In meiosis, this
can result in one gamete receiving two of the same type of
chromosome and another receiving none of this type. Nondisjunction is a cause of
gross chromosomal abnormalities.

a rudimentary internal skeleton
made of stiff cartilage that runs lengthwise under the
dorsal surface of the body of
chordates. Generally, there is a
single hollow nerve chord on top of the notochord. Among humans and the other
vertebrates, the notochord is replaced by a more
complex skeleton following the embryonic stage of development.

potentially, a chronometric dating method based on the fact that obsidian,
or volcanic glass, progressively develops a thin chemically altered outer layer due to the
absorption of water. The thickness of this hydration layer is directly proportional
to the amount of time since the rock was formed or since a fresh surface was exposed to
the elements. Since the rate of hydration varies between samples from different
volcanic sources, this technique could arguably be considered relative
rather than chronometric.

the earliest stone tool making tradition.
The first Oldowan artifacts were made in East Africa about 2.5-2.4 million years
ago presumably by Homo habilis and continued to be
made by early Homo erectusuntil about
1.5 million years ago. They consisted of simple core and flake tools
only slightly modified from their natural state by percussion flaking.

a
comparatively new radiometric dating technique similar to
thermal
luminescence. OSL is based on the fact that minerals in sediment
grains are affected by prolonged exposure to light. Specifically,
light causes electrons of the mineral atoms to be progressively dislodged.
This provides a natural clock. So far, the OSL technique has been
used to date silty or sandy water deposited sediments that are 1/2 million
years old or younger.

a hypothetical early
human and possibly late australopithecine
tool making tradition based on the
use of bones, teeth, and horns. This was proposed in the 1940's
by Raymond Dart, but most paleoanthropologists reject it today.

a bone disorder in
which there is a progressive reduction in bone density resulting in
brittleness and increased porosity. People with
osteoporosis are at a high risk for bone fractures. This disorder is
most commonly found among post-menopausal women. However, it also
occurs at a high frequency among men who have low testosterone levels
(e.g., men with Klinefelter syndrome).

the abnormal expression of a trait
in the phenotype of an individual resulting from the presence of
extra chromosomes or copies of the
genes
responsible for the trait. For example,
Down
syndrome
traits are likely the consequence of inheriting three chromosome 21's instead of the usual
two. Apparently, the genes on the extra chromosome are also expressed.

regular consumption
of too many calories. Prolonged over nourishment can result in chronic
obesity, which is associated with higher risks for type 2
diabetes, heart disease,
and some kinds of cancer. See
malnourishment.

an
experimental dating technique based on the fact that organic carbon in
soil humus and charcoal progressively convert to oxidizable carbon over
time. The ratios of these two forms of carbon vary directly with the
age of the material. This technique requires an inexpensive chemical
analysis procedure. The effective time range for OCR dating has not
yet been established.

the earliest stone
tool making traditions from the first ones made by Homo
habilis down to the most advanced ones of the last Ice Age made by
modern Homo sapiens. Paleolithic
literally means "Old Stone" Age. See
Lower,
Middle, and
Upper
Paleolithic.

dating methods based on the fact that the magnetic
north pole wanders around
the rotational north pole
and has repeatedly reversed position with the magnetic south pole at
irregular intervals in the past. There are permanent records of these movements in the
form of thermoremanent magnetism
found in burned clay and rock as well as
geological deposits of volcanic origin. Archaeomagnetic dating is
the term generally used for dating based on the wandering of the
magnetic north pole around the rotational north pole over the last
10,000 years or so. Geomagnetic reversal time
scale(GRTS)
dating and geomagnetic polarity time scale
(GPTS) dating
are terms applied to the method based on the much longer term reversals
of the magnetic poles.
The two related paleomagnetic dating methods have been considered by
some researchers to be
chronometricand
calibrated
relative by others.

Charles Darwin's incorrect theory
about the inheritance of traits. He proposed that hereditary particles
in the body are affected by the things an individual does during his or
her lifetime. These modified particles were thought to migrate via blood
to the reproductive cells and subsequently could be inherited by the next
generation. This was a variation of Lamarck's incorrect idea of the
"inheritance of acquired characteristics."

a similar evolutionary
development in different species lines after divergence from a common ancestor that
had the initial anatomical feature that led to it.
Parallelism is thought to be due primarily to the independent species
lines experiencing the same kinds of natural selection pressures. Parallelism is also referred to as parallel evolution. Parallelism
results in homoplasies.
See convergence.

members of the
hominin genus Paranthropus
described first in the 1930's by
Robert Broom.
Since the 1960's, most paleoanthropologists have not classified them
as a separate genus but, rather, as members of the genus Australopithecus. From this perspective, the
paranthropoids were the robust australopithecines. They lived during the late Pliocene and early Pleistocene
geological Epochs in Africa (i.e., ca. 2.5-1.4 million years ago). .

having five
digits
on the end of feet and hands. This trait is characteristic of all primates except
for the spider monkey which has five toes on each foot but only four fingers
on each hand. Pentadactylism is an
ancient mammalian trait that was inherited from their reptile ancestors.

a tool making
technique in which a brittle rock (e.g., obsidian, flint, chert, and basalt)
that will potentially be an artifact is struck with a heavy glancing blow from
another dense rock (i.e., a hammerstone) in order to cause a flake to be removed. An
artifact can be shaped by carefully and systematically directing the
percussion blows with the hammerstone. Percussion flaking works when a
sufficiently large shock wave is directed into the target rock so that
the
elastic limit of the material is exceeded. This causes one or more
flakes to be broken off. See pressure
flaking.

the field of view outside of the
line of direct site. Primates and most other
binocular animals only see two dimensions
(2-D) peripherally since these are
areas beyond their overlapping field of view. See
stereoscopic
vision.

chemicals
produced and secreted by an animal that can have a powerful affect on the
behavior and development of other animals (usually in the same species).
Pheromones are common throughout the animal world, including humans.

the process by which plants, algae, and some
bacteria use energy from sun light to create new organic molecules
(specifically carbohydrates) out of carbon dioxide, water, and elemental
nutrients in
specialized chlorophyll-containing cells. Most forms of photosynthesis
produce oxygen as a byproduct.

referring to the physical
moldability of an organism as it is developing. This flexibility allows
environmental forces to alter the genetically predetermined shape of our bodies to some
extent. Example: permanent changes in the shape and position of foot bones resulting
from the old Chinese practice of binding, or tightly wrapping, the feet of girls.

the original name
given by Eugene Dubois to the Homo erectus
skeletal remains from Java. Literally, Pithecanthropus erectus
means "ape-man who stands erect." This scientific
designation is no longer in use.

an
organ in the uterus of a mammal that develops from the chorion of an embryo
during gestation. The placenta is connected to an unborn child by the
umbilical cord. The placenta provides oxygen, nutrients, and
antibodies for a fetus. Following birth the placenta and umbilical
cord are naturally expelled from the uterus as the "after birth."

the relatively clear liquid medium in blood which carries the
red cells,
white cells, and
platelets. Most of blood's volume is made up of
plasma. As the heart pumps blood to cells throughout the body, the plasma brings
them nourishment and removes the waste products of metabolism. Plasma also contains salts, sugars,
lipids,
amino acids,
hormones,
and blood clotting substances.

the
sixth geological epoch of the Cenozoic Era.
The Pleistocene occurred approximately 1.81
million to 10,000 years ago.
This was mostly a time of world cooling punctuated by 3-4 major ice
ages.Most human evolution took place
during the Pleistocene.

the male sex spores of flowering
plants. Pollen particles are usually nearly invisible, except in large
concentrations, due to their extremely small size. They can survive for hundreds of
thousands of years in silty, anaerobic soils, such as mud sediments at the bottom of a
lake. When excavated from early human sites, they can be used to reconstruct what
the climate was like at the time of the occupations as well as relatively
date them.

a mating pattern
in which one female has more than one male mate. Polyandry is rare
among nonhuman primates. It is seen only among marmosets and tamarins.
Polyandry occurs in some human societies in
isolated rural regions of India, Sri Lanka, and especially Nepal, and Tibet.

an inherited trait that is
determined by genes at two or more loci. Simple Mendelian rules of
dominance do not apply to the complex interaction of these genes. As a result,
phenotypes may appear as apparent blends or
intermediate expressions. Human skin and hair
color are polygenic traits. Many polygenic traits are also influenced
by environmental factors.

a mating pattern
in which one male has more than one female mate. Polygyny is common among primates. It is found among hamadryas
baboons, geladas, langurs, howler monkeys, gorillas and many human
societies. It has been a culturally preferred marriage pattern in
numerous Native American, African, and South Asian cultures. However,
polygyny is not as common among humans as
monogamy, even in cultures that
advocate it.

a chromosomal abnormality in which
there are extra complete multiples of chromosome sets (e.g., 23 + 23 + 23).
Polyploids are rare among animals but common in plants. A
mosaic
polyploidy (with only some ployploid cells) is the common animal form. See
aneuploidy.

a more or less distinct group of
individuals within a species who
are reproductively isolated from other groups. In other words,
they restrict their mate
selection to members of their own population.
This is usually due to geographic and/or social barriers to mating with
outsiders. Members of a completely
isolatedsmall population tend to have similar
genetic characteristics due to generations of inbreeding.

the idea that if two fossils have
major similarities they should be categorized as being members of the same species.
From this perspective, minor anatomical differences within the same population are
expected since the members of living species have individual variation.People who
advocate this viewpoint are also referred to in the biological sciences and
"lumpers". See typological viewpoint.

a system for classifying people
based on the assumption that the only biologically distinct groups are long isolated
breeding populations whose evolutionary paths have separated from other populations.
Since physical and cultural barriers to interbreeding between most groups have broken
down
to someextent, this approach is of marginal value in grasping the reality of human
variation today.

after the period in a woman's life
when her ovulations and menstruations have reduced in frequency and finally stopped
altogether--i.e., after menopause. Menopause usually takes place between the ages of
45 and 55.

a radiometric
dating method based on the fact that potassium-40 in volcanic rock decays into
argon-40 and calcium-40 at a known rate. The half-life of potassium-40 is
approximately 1.3 billion years. Chronometric dates
are determined by measuring the amount of argon-40 in a sample. Similarly, argon-40
and argon-39 ratios can be used for chronometric dating.

the ability to physically grasp
something. All primates have prehensile hands. With the exception of humans,
they all also have effective prehensile feet. The larger New World monkeys (Cebidae) have
prehensile tails as well. Some marsupials living in the eastern islands of Indonesia
and New Guinea also have this characteristic.

the teeth with two-pointed crowns
located between the molars and the
canines.
In hominins, apes, and all Old World monkeys, there are two premolars in each
quadrant of the mouth. The premolars are also called bicuspids
.

a tool making
technique developed in the Upper Paleolithic
as a further refinement in shaping brittle-flaking
rock artifacts . After preliminary shaping by percussion
flaking, they often finished a tool with pressure flaking.
They used a hard pointed object, like the tip of a deer antler, to literally
push off flakes in the final shaping and thinning process. This
resulted in small, regular flake scars and much greater control in
determining the shape of the final product. Pressure flaking was also
used to retouch, or sharpen, sharp edges.

referring to the position in a site
where an object was originally deposited. Finding an artifact or fossil in primary
context allows a researcher to apply the principle of
association in dating and interpreting it. This cannot be done if the object is
in a secondary context, which is to say that it was moved to a new location after the
original deposition.

Gregor Mendel's second principle of
genetic inheritance. It states that different pairs of
genes
are passed to offspring independently so that new combinations of genes, present in
neither parent, are possible. In other words, the distribution of one
pair of alleles does not influence the distribution of another pair.
The genes controlling different traits are inherited independently of one
another.

Gregor Mendel's first principle of
genetic inheritance. It states that, for any particular trait, the pair of
genes of each parent separate (during the formation of sex cells) and
only one gene from each parent passes on to an offspring. In other
words, genes occur in pairs (because
chromosomes occur in pairs).
During gamete production, the members of each gene pair separate, so that
each gamete contains one member of each pair. During fertilization,
the full number of chromosomes is restored, and members of gene pairs are
reunited.

the assumption that if there are
layers in a sedimentary deposit, those laid down first will be on the bottom and those
laid down last will be on the top. This is the basis of using
stratigraphy as a
relative dating method.

a
proteinthat has the ability
to cause the cells that it invades to repeatedly duplicate it. Prions
are responsible for causing Mad Cow Disease.
Apparently, prions are not effectively attacked by their host's immune
system nor can they be killed with existing antibiotics, extreme heat,
cold, or other normally lethal conditions. The word prion comes from
"proteinaceous infectious particle."

any of a large number of organic
molecules that are composed of one or more chains of
amino acids.
These chains are twisted and folded back on themselves in complex
patterns. Proteins can serve a wide variety of functions through their ability to bind
to other molecules. Proteins may be transporting molecules in blood,
structural components, enzymes,
hormones,
antibodies, or
neurotransmitters.

referring to a very
rudimentary culture. Chimpanzees and possibly other great
apes as well as our fossil ancestors 3-4 million
years ago are said to have such a protoculture. While they are
dependent on their community's learned behavior patterns for survival, they
do not have complex cultural technologies like humans.

the subclass of mammal species in
which females lay eggs like birds and reptiles. However, they feed their
newborn with mammary gland secretions like all other
mammals. The Prototheriaare also referred to as monotremes, which
literally means that they have only one opening for excretion and reproduction. Included
in this subclass are the platypus and echidna.

the stage of maturation of an
individual when secondary sexual characteristics begin to develop and sexual reproduction
first becomes possible. These changes are genetically controlled and triggered by
hormones.

a pneumonia-like accumulation of fluid and swelling in the lungs.
Like cerebral edema,
it can be caused by hypoxia at high altitude. While pulmonary edema
is potentially life threatening, it generally is less likely than
cerebral edema
to result in death if treated in time.

An Upper
Paleolithic technique for making blade flakes.
After first preparing a rock core, a hard pointed punch (usually made from a
deer antler tip) is placed near the edge of a striking platform and a
percussion blow with a hammer to the top of the punch sends a controlled
shock wave into the core which removes a thin, narrow blade flake.
Upper Paleolithic cores prepared for this technique were usually conical
or cylindrical in shape with a relatively flat perpendicular striking
platform at one end.

an
evolutionary history in which a speciesremains essentially
unchanged for
hundreds of thousands or even millions of years and then experiences short
periods of very rapid evolution.
The
punctuated, or rapid change periods, are the result of major environmental
changes in predation pressure, food supply, climate, etc. During these
times, natural selection may favor varieties that were previously at a
comparative disadvantage. The result is an accelerated rate of change
in gene pool frequencies in the direction of the varieties that became the
most favored by the new environmental conditions. See phyletic gradualism.

a simple graphical method of
showing all of the potential combinations of offspring
genotypes that can
occur and their probability given the parent genotypes.
Punnett squares are commonly used
by genetics counselors to predict the odds of a couple passing on
particular inherited traits.

any of the different varieties of
humanity assumed by some people to exist, based on the discredited typological model of
human variation. Such "races" are commonly distinguished on the basis of
visibly observable traits such as skin color, hair form, and body shape. From a
biological perspective, the term race should be reserved for distinct varieties or
sub-species. In the U.S. and other nations that use
the concept of race, it refers mainly to culturally created realities
rather than biological differences.

a radiometric
dating method based on the fact that the amount of carbon-14 steadily decreases in all
organisms after death. The reduction in the frequency of this isotope
in a sample occurs at a half-life of 5730 ▒ 40 years. This technique is used to
provide chronometric dates for organic materials such as
bone, shell, wood, and charcoal.

a sample that is
selected by a researcher without any bias whatsoever. In other words,
all samples in a population have an equal probability of being
selected. This can be achieved by using a computer to randomly select
the sample.

a gene that can
initiate or block the functions of other genes. Regulator genes control the timing
of production of a variety of chemicals in humans and other organisms.
Shortly after conception, regulator genes work as master switches
orchestrating the timely development of our body parts. They are also
responsible for changes that occur in our bodies as we grow older.
Regulator genes are also called homeotic genes .

a date that gives the time of an
event only with reference to another event that is not worldwide in scale. It only
indicates that one event occurred earlier or later than another. For instance, the
observation that strata 2 is younger than strata 1 beneath it in a geological deposit does
not provide information about how many years ago strata 2 was laid down. It only
indicates its age relative to strata 1. In addition
to the use of stratigraphy,
relative dating methods include
biostratigraphy and
fluorine
analysis dating. See chronometric
date.

the process that
occurs during the rest period (interphase) at the outset of
mitosis and
meiosis by which a
DNA molecule is duplicated
or copied. One
DNA molecule becomes two identical ones. This is accomplished by the DNA molecule
unwinding and unzipping along its base pairs so that both sides can be copied by free
nucleotides. Replication is triggered by an
enzyme.

a
serum containing
anti-Rh+ antibodies given to
women
at high
risk
for having a baby with
erythroblastosis
fetalis (i.e., Rh- women with Rh+ mates).
This
must be done for the first and all subsequent pregnancies. The
injected antibodies quickly agglutinate any fetal red cells as they enter
the mother's blood, thereby preventing her from forming her own antibodies.
Since the serum given the mother is a passive form of
immunization,
it will shortly leave her blood stream.

small structures
usually near the surface of
endoplasmic reticula in the
cytoplasm of cells. Ribosomes are the sites where
proteins are assembled. Each ribosome is composed
of 3 RNA strands and 54 proteins woven into 2 separate, but entangled lumps.

a disease of the
skeletal system in which the bones are softened and often bent as a result
of vitamin D deficiency in the diet that hinders the normal development of
bones and teeth. Rickets most frequently affects malnourished
children.

a type of
nucleic
acid that is found in both the nucleus and the cytoplasm of cells. Unlike
DNA, RNA is single stranded. Messenger RNA (mRNA) carries the
genetic code from the DNA in the chromosomes and translates it
with the help of transfer RNA (tRNA) at the site of the
ribosomes
in the cytoplasm in order to assemble, or synthesize,
proteins.

referring to a stomach with
"saccules," or sack-like compartments, in which bacteria slowly break down
cellulose, thereby providing more useable calories. Among the primates, only the
Colobinae (colobus, langurs, and proboscis monkeys) have this characteristic. Cows
and some related animals also have sacculated stomachs.

a ridge of bone projecting up, from
front to back, along the top midline of the skull. It serves as a muscle attachment
area for the temparalis muscles that extend up both sides of the head from the mandible
(jaw). The presence of a sagittal crest indicates that there are exceptionally strong
jaw muscles. Some Australopithecus afarensis and the robust
australopithecines (Australopithecusrobustus, boisei, and aethiopicus)
had sagittal crests. Among the living primates, the most prominent
sagittal crests are found on adult male gorillas. Humans do not have them.

environmental pressure that is
placed on individuals within a population that results in change of the genetic makeup of
the next generation. Selective pressure is the driving force of
natural selection.

a
relative
dating method based on the fact that artifact types change through time in frequency
as a result of new technologies, styles, and available construction materials. The
frequency of artifact types in a stratum can be compared to known frequency changes
previously recorded for an ancient culture. In this way, the stratum can be dated
relative to other strata or sites. When a seriation
sequence has been cross-calibrated with reliable chronometric dating
methods, it can be considered a
calibrated
relative technique.

the X
and Y chromosomes which are responsible for determining
whether an individual is a male or a female. Normal males inherit an X from their mother and a Y from their
father. Normal females get an X chromosome from both
parents. See SRY gene.

referring to anatomical
differences between males and females of the same species.
Primate males are usually significantly
larger and more muscular than females. This is especially true of
semi-terrestrial
monkeys and the great apes.
Humans are also sexually dimorphic.

a nearly hairless large swollen patch of skin around
the genital area of females that becomes very prominent when
they are in estrus.
These areas swell with fluids and turn bright pink or red due to hormonal
changes that occur in preparation for ovulation. The sexual skin also
produces odors that excite males of the species. They become highly
attentive to the females at this time. Sexual skins are found among
many of the Old World monkey speciesin the
subfamily Cercopithecinae (e.g., baboons)as well as the chimpanzees and bonobos.

a genetically inherited
recessive condition in which red blood cells are distorted
resulting in severe anemia and related symptoms that are often fatal in childhood.
Sickle-cell trait is the result of a
pleiotropic gene.
People who are heterozygous for this trait rarely have these
debilitating and ultimately fatal problems but do have a high degree
of immunity to malaria. Sickle cell trait is at its highest
frequency among Central African populations and among people whose
ancestors came from that region.
Sickle-cell trait is also known as sickle-cell anemia.

the original name
given to the Homo erectus skeletal
remains from the limestone cave site at Zhoukoudian
near Beijing,
China. Sinanthropus pekinensis literally
means "Chinese man from Peking" or Beijing. It has also been
called "Peking Man."

a traditional
land-clearing practice whereby trees and other dense vegetation are cut
with axes or machetes and
later burned. Ash from the burned vegetation provides fertilizer for
agricultural crops that are planted among the remaining tree
stumps. Since no other fertilizer is usually applied, fields are
abandoned after a few years, when crop yields go down, and clearing occurs
elsewhere. Traditional slash-and-burn farmers use
simple, hand-held digging sticks instead of plows.

all the
cells in the body except those directly involved with reproduction. Most cells in multicellular plants and
animals are somatic cells. They reproduce by
mitosis and have a
diploid number of chromosomes. See
sex
cell.

a wood or bone rod with a hook on one end
that fit into a socket at the base of a spear.
This device was used by the
Cro-Magnon and
other people with
Upper
Paleolithic technologies to push off spears.It increased the range and force of
impact of projectiles by essentially increasing the length of
the spear thrower's arm. The spear thrower is also known as an atlatl .

the idea that all life forms were
created by God as separate, distinct species. The implication is that they do not
change through time and that there is no evolutionary relationship between different
species.

the evolution of new
species from older ones.
When this occurs in a single evolutionary line without
branching, it is referred to as successive speciation and results in the pattern of evolution known
as
anagenesis .

the largest natural
population of organisms that can potentially
interbreed to produce fertile offspring. It is
commonly assumed that members of one species are reproductively
isolated from members of all other species (i.e., theycannot mate with them to produce fertile offspring).
However, we must be cautious in defining species with this criterion
because members of very closely related species can sometimes produce
offspring together, and a small fraction of those may be fertile to some
degree. This is the case with mules, which are the product of mating
between horses and donkeys. About one out of 10,000 mules is fertile.
This suggests that some species differences are a matter of degree.
Seemorphospeices, biospecies,
and paleospecies.

a
neural
tube birth defect in which there are malformations of vertebrae and the
protrusion of the spinal cord from the body. This can result in paralysis of the
legs, loss of bowel and bladder control, and "water" on the brain
(hydrocephaly). Spina bifida requires surgical correction.

sex-determining region Y gene. A gene on the Y
chromosome which, if present and functioning, causes the undifferentiated sex organs of an
animal embryo to become testes. These then produce the hormone
testosterone which, in turn, causes the development of
masculine physical traits.

Selection against extreme forms of a trait.
In the case of polygenic
traits that are expressed as a continuum of
phenotypes, such as human
stature, it would be selection for people who
are in the middle of the range and against those who are very tall or
very short. The result would be fewer people
who are at the extremes in height. In the case of a trait
controlled byonly two alleles, it
would be selection against both
homozygotes and for the
heterozygote. An example is nature selecting
for people who are
heterozygous for the
sickle cellallele in
a malarial environment.
See directional
selection and
disruptive selection.

a statistical measure of the
dispersion (or spread) from the arithmetic mean (or average) of a group of scores.
Chronometric dates derived with a
radiometric method are published with a "plus or
minus" factor, which usually is a range of dates within one standard deviation above
and below the mean. This should be read as a 67% likelihood that the actual date
falls within the given range.

embryonic cells that have not yet
become specialized tissue cells--they potentially can develop into any
type of tissue in the body. Children and adults retain somewhat
specialized stem cells in their bone marrow. These stem cells are
the source of the major blood cells--erythrocytes,
leukocytes, and
thrombocytes (platelets).

defective
alleles
that have segments which are doubled in their transmission from generation to
generation. In the case of genetically inherited diseases, the result is
increasingly severe symptoms each generation. The myotonic form of
muscular dystrophy is an example. Stuttering
alleles are also known as unstable alleles.

referring to sources of food and the way they are
obtained (e.g., scavenging, hunting, and farming). Subsistence
base is another name for subsistence pattern.
"Subsistence strategy" refers to decisions made by people as to the best
way to obtain food in a particular environment (e.g., diversified
foraging, specialized big game hunting, etc.).

referring to
climatic regions that are next to the arctic circle (e.g., Northern Alaska
and Northern Canada) and that have extremely long cold winters with a great
deal of snow and little or no day light. Subarctic regions are farther
north than temperate ones in the northern
hemisphere.

the idea that those
individuals in a species that have characteristics selected for by nature are biologically
the most fit. They are the ones who more frequently survive to be the parents of the next
generation. The fittest individuals are not necessarily the strongest, largest,
quickest, or smartest. This concept was central to Charles Darwin's
idea of natural selection.

a magical practice
based on the principle that like causes like. For those who believe
that this works, it would be possible to cause another person or animal harm by making
an image of them and doing something to harm the image such as painting a
spear sticking into the body. The animal of whom the image is a
likeness would supposedly suffer the same effects. The Cro-Magnon cave paintings of animals
being wounded or pregnant was very likely attempts to use
sympathetic magic to
cause the same effects on the real animals.
Sympathetic magic is also called imitative magic.

the 20th century conception of
evolution being caused by a number of complex and often interacting
processes. This is essentially a combination of Darwin's concept of
natural selection, Mendel's basic genetics, along with the facts and theories of
population genetics and molecular biology.

naming, describing, and
classifying organisms into different categories on the basis of
their appearance and other diagnostic characteristics
as well as their evolutionary relationships. The biological sciences primarily use the Linnaean classification
system for this purpose.

a genetically
inherited condition caused by the inability to produce the enzyme hexosaminidase A. This results in progressively increased fluid
pressure on the brain and the subsequent degeneration of the brain and nervous system
beginning about 6 months of age and inevitably resulting in death usually by
age 2-3. The gene responsible for Tay-Sachs Disease is
recessive. It has been most common among the descendents of Eastern
European Jews (Ashkenazi Jews).

lateral and/or vertical movement of
segments of the earth's crust. The continents and the ocean floors consist of
tectonic plates that are moving relative to each other. On average, such movements
are about 1 inch per year.

active defense by
community members of their shared home range or territory. Many
species of non-human primates use scent marking, loud vocalizations, or
threat gestures to defend their territories against incursions by other
communities of their species.

a class of masculinizing
hormones. Both men and women produce them, but males normally
produce much more. Testosterone is mainly produced in the
testes
of males. Smaller amounts are produced by the cortex of the adrenal glands in both
males and females.

a group of
genetically inherited forms of anemia caused by the production of fragile
hemoglobin molecules that are easily destroyed. Thalassemia is most
common around the Mediterranean Basin and in Southeast Asia. As in
the case of sickle-cell
trait, and glucose-6-phosphate dehydrogenase deficiency, it may provide some
immunity to malaria.

a radiometric
dating method
based on the fact that trace amounts of radioactive atoms, such
as uranium and thorium, in some kinds of rock, soil, and clay produce constant low amounts of background ionizing
radiation. The atoms of crystalline solids, such as pottery and rock, can be altered
by this radiation. Specifically, the electrons of quartz, feldspar, diamond, or
calcite crystals can become displaced from their
normal positions in atoms and trapped in imperfections in the
crystal latticeof the
rock or clay molecules.
These energy charged electrons progressively accumulate over time. When a sample is
heated to high temperatures in a laboratory, the trapped electrons are released
and return to their normal positions in their atoms. This
causes them to give off their stored energy in the form of light impulses (photons).
This light is referred to as thermoluminescence
(literally "heat light"). A similar effect can be
brought about by stimulating the sample with infrared light. The intensity of
thermoluminescence is directly related to the amount of accumulated changes produced by
background radiation, which, in turn, varies with the age of the sample and the amount of
trace radioactive elements it contains.

magnetic fields that are altered or
formed in atoms of iron by heat in excess of 1100░ F. (600░ C.). Such fields line up with the
magnetic field of the planet at the time of the exposure to a high temperature. They will remain oriented to that direction indefinitely despite the fact that the true
position of magnetic north wanders over thousands of miles around the rotational north pole and even reverses with the
magnetic south pole over longer periods of time. See
paleomagnetic dating.

a bone or
antler harpoon tip or
point with a hole for attaching a rope. It is designed so that when
the harpoon is thrust into the body of a large animal, the wooden shaft
falls off. The hunter keep holds of the animal with the rope attached
to the toggle-head harpoon point stuck in its body.

a form of
RNA
that binds to specific amino acid molecules and
transports them to the ribosomes for the assembly of
proteins.
Transfer RNA molecules temporarily bond with corresponding
messenger
RNAcodons at the ribosomes in this process of
protein synthesis.

a structural modification of a
chromosome in which a portion of a chromatid is broken off and
attached to a different location on that
chromosome or on
another chromosome. This occurs as a result of
crossing-over.

the form of
aneuploidy
in which there are 3 chromosomes instead of just 2 for a specific
homologous pair. An example is the common form of
Down syndrome in which there are 3 chromosome 21's.
Most fetuses with autosomal trisomies die before
birth.

a rare chromosomal
abnormality in which there is a
trisomy of chromosome
18. This inherited condition is also called Edward's syndrome. It is
characterized by severe mental retardation, a small head with malformed ears set low, and
a face with a pinched appearance. Other likely defects include a cleft palate,
webbed hands, missing thumbs, clubfeet, as well as heart and genitourinary
defects. Individuals with trisomy 18 usually die within a few months after birth.

referring to the
usually warmest climatic
regions. They are mostly found within 20░-30░ latitude from the
Equator. All human evolution until relatively late Homo
erectus occurred in the tropics, especially in Africa. See
subtropical
and temperate.

a genetically inherited
sex chromosome abnormality only affecting females. Women
with Turner's only have one X chromosome--their
genotype is X0.
These individuals are short in stature, averaging 4'7" and have distinctive
webbed necks (i.e., extra folds of skin). They have exceptionally small breasts and
generally lack secondary sexual characteristics. Their ovaries do not develop
normally and they do not ovulate. They are in a sense
postmenopausal
from early childhood and are sterile. In some individuals, there is slight mental
retardation. Turner syndrome is rare--current estimates of its
frequency range from 1 in 3000 to 1 in 10,000 females.

a system for classifying people
based on the false assumption that humans can be unambiguously placed into
"races" on the basis of selected traits such as skin color, hair form, and body
shape. Advocates of this approach incorrectly believe that there are more or less
distinct populations of people from different geographic regions. Negroid,
Mongoloid, and Caucasoid are examples of typological groupings.

the idea that if two fossils look
slightly different, they must be categorized as being from two different species.
This approach emphasizes minor differences. People who maintain this approach are
generally referred to in the biological sciences as "splitters". See
populationist viewpoint.

the use of high frequency sound to
form an image or picture of internal organs for immediate medical diagnostic
purposes. The Ultrasonography device transmits sound waves directly into the body
and then accurately records the amount of time for echoes to return to a receiver, much
like radar. The sound waves used are at frequencies above the threshold of human
hearing--e.g., 20,000 vibrations per second.

electromagnetic radiation ranging
in wave length just beyond violet in the visible spectrum of light.
The human eye cannot detect u.v.Our sun is
the
major source of u.v. radiation on earth. Prolonged exposure to u.v. can result
in destructive skin burns and can promote the onset of skin cancer.

the late 18th century theory of
James Hutton that the natural forces now changing the shape of the Earth's surface have
been operating in the past much in the same way. The most important implication is
that the Earth is very old and that the present is the key to understanding the
past. Elaborated on by Charles Lyell in the 19th century, this theory opposed
catastrophism.

Gregor Mendel's idea that the
characteristics of parents are passed on to descendants unchanged as units. In other
words, the hereditary material of any organism is made up of discrete units (now called
genes).

a time scale, or calendar, that can
be used any place in the world since it has a finite beginning point from which any
earlier or later event can be related exactly. All chronometric
dates are given in terms of a universal time scale.

the last part of the
Paleolithic
stage of development
in which Cro-Magnon and other late ice age modern
Homo
sapiens developed a number of sophisticated stone tool making
traditions including the Magdalenian. This was the height of technical
sophistication during the Old Stone Age. The Upper Paleolithic in
Europe began about 40,000 years ago and ended around 10,000 years
ago. Technological developments leading to the
Upper Paleolithic may have begun somewhat earlier in Africa.

a radiometric
dating technique based on the rate at which uranium-238 and thorium-230 fission.
This method has been used to date organic marine sediments, bone, wood, coral, stone, and
soil from deep water, cave, or land fall areas. The time range that has been dated
with this method so far is less than 300,000 to about 1,000,000 years ago. The
half-life of U-238 is 4.468 billion years and the half-life of Th-230 is 75,380
years. This is one of several uranium series dating
methods.

the expression of a genetically
inherited trait in different forms or degrees in different people. For example, the
alleles for the Down syndrome genes may cause an effect
in the phenotype of some individuals but not others. As a
result, there is considerable variability within the Down syndrome population in regards to
susceptibility to the characteristic unpleasant medical problems.

acalibrated
relative or potentially
chronometric
dating technique based on counting annual silt
deposits (i.e., varves) in former lakes resulting from the summer melt of glaciers.
In Scandinavia, this geological clock has been used to date associated archaeological
evidence from the melt years of the last ice age, which began its final retreat about
15,000 years ago.

small carvings of
women that could fit into the hand made by the Cro-Magnon
people. They were not portraits but rather faceless idealized
representations of well fed, healthy, usually pregnant women with large
buttocks. Because of these characteristics, they are thought by
most paleoanthropologists to be ritual objects symbolizing female
fertility. Many of these stylized carvings are reminiscent of
modern abstract art. Venus figurines were made from 27,000 years
ago down to the end of the last ice age 10,000 years ago.

a category of extremely small
microscopic parasites of plants, animals, and bacteria. Viruses are not cells but rather
RNA or
DNA molecules surrounded by a
protein coating. Since
viruses cannot reproduce without a host cell, they are not strictly speaking living
organisms. There are many kinds of
viruses.

a genetically inherited
sex chromosome abnormality only affecting males. Men with
XYY syndrome inherit an extra Y chromosome--their genotype is XYY. They are usually
quite tall (i.e., above 6 feet) and generally appear and act normal. During
adolescence, they frequently have severe facial acne. They are usually fertile and
lead ordinary lives as adults. Many, if not most, are unaware that they have a
chromosomal abnormality. The frequency of XYY syndrome is not certain due to
statistical differences between different studies of this condition. It may be as
common as 1 in 900 male births to as rare as 1 in 1,500 or even 1 in 2,000.

a bony arch extending horizontally
on either side of the face just below the eyes on primates and many other vertebrates.
The major jaw muscles pass under these two arches on their way up to the temporal
areas of the skull for attachment.

a
"fertilized" ovum. More precisely, this
is a cell that is formed when a sperm and an ovum
combine their chromosomes at conception. A
zygote contains the full complement of chromosomes (in humans 46) and has
the potential of developing into an entire organism.